The present invention is in the technical field of wireless transmission and reception of information. More particularly, the present invention is in the technical field of ultra-low power backscatter radio communication. Embodiments and aspects of part of the invention described herein, focus on digital bistatic backscatter radio; the illuminator of a tag and the receiver of the backscattered information (from the tag) are distinct units, located at different points in space.
The illuminating signal may be modulated and/or emitted from legacy wireless systems or infrastructure (ambient case).
Embodiments and aspects of part of the invention described herein, are inspired by recent findings in digital bistatic backscatter radio [Bletsas et al 12a], [Bletsas et al 12b], [Bletsas et al 13] (where the illuminating signal is unmodulated) and ambient backscatter radio (where the illuminating signal is modulated and carries its own information). Although easy and straightforward to implement, current methods [Smith et al 13] and [Smith et al 14] either exploit on-off keying (OOK) modulation at the tag or utilize detection schemes with significant trade-offs between communication range and information transmission rate. Additionally, the structure and/or modulation of the ambient signal is explicitly considered. Moreover, current methods require multiple access from multiple tags utilizing time division multiple access (TDMA) or code division multiple access (CDMA), which increases complexity and cost of the overall system. Methods for analog ambient backscatter have been also proposed [Smith et al 17] and [Bletsas et al 17]. Such methods provide analog information transmission, while requiring a frequency modulated (FM) ambient carrier to operate according to their intended purpose.